Emotion processing in the minimally conscious state.

As a newly described condition distinct from coma or the vegetative state, minimally conscious state (MCS) is characterised by a threshold level of consciousness, and diagnostic criteria have recently been proposed. 1 In MCS, cognitively mediated behaviour occurs inconsistently, but is reproducible or sustained enough to be differentiated from reflexive behaviour. It is clinically essential to distinguish this condition from persistent vegetative state (PVS), due to a potentially more favourable outcome. 1 So far, whether patients in MCS can process emotion is unknown. Cortical processing has been described in PVS using auditory and visual functional paradigms with positron emission tomogra-phy. 2 3 However, to date hardly any functional imaging studies are available in patients in MCS. 4 We used fMRI to assess brain activity induced by an emotional stimulus in a patient in MCS. A 17 year old man was riding his bicycle when he was hit by a train. The accident resulted in head trauma and immediate coma, progressing to MCS over the course of 4 months, when he was admitted to our institution. This research protocol was approved by the Institutional Ethics Committee. At the time of the fMRI study, 5 months after the accident, the patient localised noxious stimuli, had spontaneous eye opening, detectable sleep/wake cycles, sustained visual fixation, and contingent smiling, thus meeting criteria for MCS. A structural MRI study showed mild cortical atrophy and dilated ventricles. Auditory evoked potentials showed decreased conduction velocities at brainstem level. The patient increased his level of awareness 2.5 months after the functional study was conducted. Auditory evoked potentials after recovery were within normal range, while MRI showed much less ventricle dilatation. Six months after recovering full consciousness, he was able to chat normally and feed himself. Currently we are retesting the patient with the same paradigm. Non-familiar voice v silence and mother's voice v non-familiar voice recognition were tested in an fMRI block design with 30 seconds per epoch. The patient listened to his mother reading a story, followed 30 seconds later by an age matched voice reading the same story, for 30 seconds with silence epochs in between. Blood oxygen level dependent images were acquired using a T 2 weighted gradient echo planar sequence on a General Electric Signa CVI, 1.5T system with real time image processing of multislice and multi-phase images during patient stimulation and rest periods. The Medx 3.4 Sensor System was used to carry out …